The Grenada gazette. (Grenada, Miss.) 1885-18??, 1887-12-03
CONCERNING O oUDs.


atmosphere. II it rests upon tho
a Of the earth We call it a fog.
~, seo smass of vapor on the sum.
VT 81 q high mountain and We call
" cloud, but if we climb to the top Of
.ss~ mountain and find ourselves in the
land we see it to be simply a fog. To
wv observation, clouds take on forms
.sat are almost infinite in variety,
1st they may be divided into six
.lasses. each presenting quite distinct
CHARACTERISTICS. These are known as
cirrus. cumul us and stratus cloud, as
.implo div isions; and cirro-cumulus,
o;rro.stratus and cumulo-stratus as
compound divisions. The cirrus
s1oud consists of long, slender. fla
ments, either parallel or diverging
from each other. These clouds have
the greatest elevation and the least
density of MI clouds. Even in fair
weather the sky is seldom free from
small distant groups of cirrus clouds.
They are thought to be made up Of
spicule Of ice or flakes of snow, since
At the great height at which
they float, from five to eight miles
above the earth, the temperature of
the air is below freezing point even in
midsummer. The cumulus cloud is
much denser than the cirrus, and is
formed nearer the earth. 1t usually
has the form of a hemispherical or
convex mass with horizontal base.
This is the cloud often seen in large
masses near the horizon, looking like
huge mountains Of snow. The round
ed top of this cloud results from the
mode of its formation. As the earth
is heated by the SUMS rays, currents
Of warm air rise, carrying with them
invisible vapor. When they reach a
certain height this vapor is condensed
and forms cloud, and since the upward
motion is greater under the center of
the cloud, the vapor is then carried to
its greatest height. The stratus cloud
is q widely-extended. horizontal sheet,
often covering the entire sky, and
and hanging so low that it frequently
touches the carth's surface in the
form Of a fog. For the compound
notifications of cloud forms, the cir.
ro-cumulus is seen in small rounded
masses, often very near together. On
account Of their fleecy appearance,
these are often called 'woolly clouds.'
This cloud is very frequent in summer.
but seldom precedes rain. The GIRO
stratus consists Of fibrous clouds
spread out in strata, which are
either horizontal or slightly in-
clined to the horizon. Sometimes the
whole sky is mottled with the cloud.
like the back Of q mackerel,
and, therefore, is called a mackerel
sky. This cloud always presages wind
and rain. The cumulo-stratus is the
large dark cloud formed by the mass.
ing Of the fleecy cumulus in great
These clouds are to be seen in
great magnificence on the approach of
. thunderstorm. and are, therefore.
often called 'thunder heads" Some
meteorologists also classify with the
above the nimbus cloud, which is a
stratus cloud from which rain is fall
ing. but others do not think it worth
while to keep this division. The
of q cloud is measured by
trigonometrical rule by observing its
simultaneously at two sta.
tlUns. In mountainous countries It
can be compared with the peaks near
which it passes. Most accurate re-
suits, however. are obtained by ascend
ing in a balloon and noting the height
of the barometer when entering the
cloud and again when emerging from
it, the barometer giving the meal of
computing corresponding attitudes.
The height of clouds is very variable
The stratus. as we have said, often
descending to tho earth. In pleasant
weather tho lower limit of cnmulus
clouds varies from 5000 to 6. 1000 feet
elevation. and their upper limit from
., 900 to II, 900 feet. Cirrus clouds never
descend below tho summit of Mount
Blanc, which has q height of l5,744
feet, and arc often seen to be fur above
mountains that are 10000 to %, 900
feet high. II is estimated, however,
that they would not he visible at a
height exceeding ten miles. In verti-
cal thickness clouds are supposed to
seldom exceed half n mile, but tho
masses of cumulus are
sometimes estimated at over three
miles. Clouds move with the wind,
and there is no way Of estimating their
movement but by measuring the
velocity of the wind currents. Clouds
reflect light, Of course, or they would
not be visible; such light as can pass
through them is rcfracted out Of its
path by the presence Of the vapor
particles. Thus, when VIC sec objects
through a fog we often notice that
they are distant from their true posi-.
ton or unnaturally magnified. The